Pediatric RSV Hospitalizations Reveal Shifting Risk Profiles Post-Pandemic

Pediatric health systems experienced a resurgence of respiratory syncytial virus (RSV)-associated hospitalizations in 2022 and 2023. The disruption of typical viral circulation patterns raised concern that previously understood risk factors for severe RSV disease—such as young age, prematurity, and chronic conditions—may require expansion to maintain predictive value in the current epidemiologic context.

To evaluate this, an observational cohort study published in April 2025 in JAMA Network Open looked at the cases of 709 children hospitalized with laboratory-confirmed RSV at two Canadian tertiary pediatric hospitals over a one-year period.

The study aimed to reassess risk profiles for severe outcomes, including intensive care unit (ICU) admission and the need for mechanical ventilation, with particular attention to both infants and older children, whose representation in severe RSV cases has increased since the pandemic era.

Disease Severity

Among the 709 cases reviewed, severe illness—defined as requiring noninvasive or invasive ventilation or resulting in death—was documented in 204 children.

The median age of all hospitalized patients was 13.1 months, but severity disproportionately affected both the youngest and oldest ends of the pediatric spectrum. Infants younger than three months accounted for more than half of the severe cases, while children aged five years and older also demonstrated elevated rates of ICU admission and ventilatory support.

These findings suggest that RSV severity is no longer confined to early infancy and now affects broader age groups with increasing clinical significance.

Age and Risk

For children younger than two years, age under six months and a history of preterm birth were the dominant risk factors for severe outcomes. Infants born before 35 weeks’ gestational age also had a significantly higher likelihood of requiring respiratory support. Notably, chronic medical conditions did not independently increase the risk of severe RSV disease in this age group once age and gestational history were accounted for.

In contrast, among children aged two years and older, chronic comorbidities played a more defining role. Pulmonary disease and home oxygen use were associated with more than double the risk of severe disease, and neurologic, neuromuscular, or developmental conditions also conferred elevated risk.

These results demonstrate that chronic health conditions, though less consequential in the youngest infants, become key predictors of poor outcomes as children age.

Rapid Progression

The duration of symptoms before hospitalization provided another lens into disease trajectory. Children who experienced shorter intervals between symptom onset and hospital admission were more likely to develop severe disease, particularly those who required ICU-level care. Each additional day of symptoms before admission correlated with a lower adjusted risk of severe outcomes. This suggests that rapid clinical deterioration may be an early marker of severity, independent of age or comorbid status.

In terms of clinical presentation, increased work of breathing, apnea, tachypnea, and cyanosis were frequently observed in children with severe illness. While these findings align with traditional markers of respiratory distress, their predictive utility may gain importance in settings where early severity scoring tools—most of which are validated only for infants—are underutilized or not yet adapted for older children.

Coinfection

Additionally, viral coinfection occurred in roughly 26 percent of children in the cohort, but most co-pathogens did not significantly alter risk for severe RSV disease.

An exception was seasonal coronavirus, which was associated with increased severity in children aged two years and older. Other viruses, including influenza, rhinovirus, and SARS-CoV-2, were not independently linked to worse outcomes.

These findings suggest that while co-infections remain epidemiologically relevant, they may not substantially affect clinical course in most RSV cases.

Policy Implications for Prophylaxis

The study’s findings directly inform current debates on RSV prevention.

With long-acting monoclonal antibodies such as nirsevimab becoming more widely available, questions have shifted from efficacy to eligibility. The data support universal prophylaxis in infants, particularly those under six months or born prematurely, as these groups carried the highest burden of severe disease regardless of comorbidity status.

For older children, the case for targeted prophylaxis is increasingly compelling. Children over age two with chronic pulmonary or neurologic conditions experienced elevated risks comparable to those historically seen in high-risk infants.

Existing international guidelines limit prophylaxis to the first two years of life. However, these findings suggest that expanding eligibility to include older children with high-risk conditions may better capture those most likely to benefit.

Surveillance and System Readiness

Over one third of the hospitalized children required ICU care, and more than a quarter received noninvasive ventilation. Transfers from community hospitals accounted for 41 percent of the cohort, indicating the systemic pressure during the seasonal surge. Yet most hospitalized children had no underlying condition, underscoring the unpredictability of RSV and the limitations of risk stratification alone.

As the RSV landscape continues to shift, particularly in the wake of altered immunity profiles post-COVID-19, ongoing surveillance will be necessary to determine whether these patterns represent temporary disruptions or lasting epidemiologic change. What is evident now is that risk is no longer defined by infancy alone. For some older children with chronic conditions, RSV poses a renewed threat—and preventive strategies will need to adjust accordingly.

Reference:
Kirolos N, Mtaweh H, Datta RR, et al. Risk Factors for Severe Disease Among Children Hospitalized With Respiratory Syncytial Virus. JAMA Netw Open. 2025;8(4):e254666. Published 2025 Apr 1. doi:10.1001/jamanetworkopen.2025.4666